The Mets are going to be atop the NL East at the beginning of the month. But not just any month.

Fred Wilpon more than a decade ago famously — or infamously — established a mandate for each Mets season: to play “meaningful games in September.”

Don’t pooh-pooh it. It is a rung — a bottom rung, at least — that many (if not all) MLB organizations set. It means retaining local fan interest as the NFL beast is about to begin its season. It means revenues continue to flow in this year, and prices for the following season (for seats and advertising and more) can be based on a contending team.

And it means, well, that meaningful games are going to be played in September.

For the Astros and Mets, it is the first time that could be said since 2008, for the Cubs since 2009.

Fred and Jeff Wilpon in spring trainingCharles Wenzelberg

It shows how precious this actually is. The baseball season is a novel, unfolding slowly over many chapters. You stick with it hoping for the payoff in the end — or, in baseball’s case, the playoff in the end.

Wilpon continued what is now a multi-year policy not to talk publicly about the team by declining a request for an interview on the subject of a meaningful September.

But even without the Mets patriarch’s words, it is not hard to decipher the meaning, beginning at the ownership level.

Because have you noticed what is missing since the Mets aggressively added to their roster at the July trade deadline and surged to the NL East lead? The relentless calls for the Wilpons to sell the franchise.

It seemed to me Mets ownership was always looking for a more nefarious, personal reason for the criticism they endured than the obvious — the team wasn’t winning. The fans wouldn’t care if the payroll were $4 if the Mets were playing for championships. They wouldn’t care about the association with Bernie Madoff if there were continuing meaningful Septembers.

You know how we know? Because of the Yankees. It is easy to forget, but George Steinbrenner used to be a villain in these parts, coinciding — by the way — with the playoff wasteland that was 1982-94. Steinbrenner is now remembered more as kindly grandfather than a twice-suspended tyrant. You think these last five championships have something to do with that?

And have you noticed that as long as Alex Rodriguez hits, how few people mention Tony Bosch, his own version of Madoff?

There also is meaning for Sandy Alderson. Before this season even began, a biography for which he was a willing participant was released called “Baseball Maverick: How Sandy Alderson Revolutionized Baseball and Revived the Mets.” That title was going to be used for many punch lines if the team failed this year. Instead, Alderson’s long-term patience to grow his fire-throwing rotation mixed with his July aggressiveness to upgrade the lineup actually has revived the Mets.

But if this team could win the division — and more — Alderson could be sitting on a different Hall of Fame case as father of the great A’s teams of the late 1980s and now this group.

Perhaps no one has more hanging on this September than Terry Collins. He has an option for next season that has not been picked up. He might be the NL Manager of the Year if this month goes well. He might be fired if it does not.

David WrightPaul J. Bereswill

As for the players, David Wright could speak to how precious — and precarious — a chance to win is. In 2006, the Mets lost in the NLCS, but with their nucleus, it felt as if they would be back in the postseason over and over. But you seize the moment in the present. Tomorrow is not promised — ask the Nationals chasing these Mets while trying to ward off the reputation as one of the great squanderers of talent in MLB history.

Or remember — if you dare — the 2007 and 2008 Mets. Who failed to hold big leads.

In September.

Buck Showalter has told me many times how endless this month feels. How the finish line is in view, but seems as if it never arrives. Yes, the value of a win and a loss are the same in April as in September. But not the meaning. In April or May or June, no one is talking magic numbers or feeling the euphoria or devastation of each win, each loss. The tension and drama mount.

The meaning of these “meaningful games” brings a pressure to each page toward the end of the long novel. It is thrilling and exasperating and makes you want to wake up for more of the same sweat and range of emotions the next day.

The first five months are prelude. Finally, for the Mets, the final month is not just to finish a schedule. Instead, they have one of the delicacies for every team and every fan: